Can someone explain this matchmaking madness to me?

Usually matchmaking is supposed to match with with equally skilled teammates and supposed to pitch you against an equally skilled team.

But why am I either matched with a super-stomp team that is coordinated, way above me in terms of skill and just carries me without me doing anything, OR matched with feeders and trash so bad and worthless ya couldn't carry them even if you were the grandmaster rank one über-gosu 9000.

There are omly these two extremes. And once every blue moon I have a normal, fun game, but apart from that rare occasion it's either boring or frustrating.

Also: what the fuck did I do to get matched with a toplane that dies EIGHT FREAKING TIMES in 10 minutes despite not even being ganked? AND HOW THE HELL DID THAT PERSON EVEN GET INTO GOLD?

Riot, you have some serious explaining to do. I have been Bronze 5 and platin 5. I've seen a wide range of skill differences. But why am I in gold and matched with people who are obviously below silver level in terms of skill? it makes no sense?!